JP5903831B2 - Composition for substrate surface protective film and method for producing substrate - Google Patents

Description

  The present invention relates to a composition for a substrate surface protective film and a method for producing the substrate, and more specifically, after forming a fine structure on the surface of the substrate, when processing the back surface of the substrate, or temporarily storing or moving the substrate. In particular, the present invention relates to a composition for a protective film used for protecting the fine structure, in particular, a composition for a substrate surface protective film suitable for protecting a deep microstructure, and a method for producing a substrate using the same.

  In the manufacture of an electronic component mounting substrate, a micromachine mounting substrate, and the like, a method of covering a substrate surface of a semiconductor, glass, organic material or the like having a fine structure formed on the surface with a protective film is used. For example, a method of covering a substrate surface with a protective film when storing and transporting an electronic component substrate on which an integrated circuit is formed is used. Further, after forming a fine structure on one surface of the substrate, a method of covering the substrate surface with a protective film is used to protect the fine structure when the other surface is processed. For example, at the time of manufacturing a microelectromechanical element also referred to as a micromachine or a MEMS (hereinafter also simply referred to as a MEMS), after forming a fine structure having unevenness of several tens of μm or more on one surface of a substrate such as a semiconductor, the back surface Is further processed. In this way, the MEMS manufacturing method processes the front and back surfaces of the substrate, and also has a so-called deep structure having a recessed portion, so that uneven steps formed on the substrate form an integrated circuit on the semiconductor substrate. Compared to the case, the manufacturing method is significantly different from the process of forming an integrated circuit on a semiconductor substrate.

  As a coating composition for a protective film on a substrate, several compositions using a phenolic resin are disclosed (for example, see Patent Documents 1, 2, and 3). However, these coating compositions have a problem of lack of flexibility due to the phenolic resin, and particularly have a problem in crack resistance during heating. Moreover, the resin embedding performance with respect to the deeply uneven fine undulations is insufficient. Moreover, the composition for protective films using water-soluble resins, such as polyvinyl alcohol, polyvinyl pyrrolidone, a water-soluble cellulose derivative, is also disclosed (for example, refer patent document 4). However, this protective film composition is used for protecting integrated circuits, and does not enable sufficient protection against a substrate having a larger uneven step such as MEMS. Further, the adhesiveness of the protective film may adversely affect the manufacturing process.

JP-A-1-236632 JP 7-38016 A JP 2010-62495 A JP 2011-29422 A

  Accordingly, the present invention provides a composition for a substrate surface protective film that has excellent crack resistance, has good resin embedding performance with respect to deep concave and convex portions such as MEMS, and suppresses adhesiveness of the protective film, and uses the same. An object of the present invention is to provide a method for manufacturing a substrate.

As a result of studying the above problems, the inventor of the present invention combined a low Tg thermoplastic resin with a specific weight ratio to a phenol resin having a high softening point, thereby suppressing adhesiveness and crack resistance and embedding property. It was found that an excellent protective film can be formed.
Accordingly, the present invention contains a phenol resin having a softening point of 140 ° C. or higher measured by a ring and ball method, a thermoplastic resin having a Tg of 70 ° C. or lower, and an organic solvent, and comprises a phenol resin and a thermoplastic resin. The composition for a substrate surface protective film having a content weight ratio of 100: 40 to 100: 300 and a viscosity at 25 ° C. of 4 to 10,000 mPa · s.
The present invention also includes a phenolic resin having a softening point of 140 ° C. or higher, a thermoplastic resin having a Tg of 70 ° C. or lower, and an organic solvent on a micro-processed substrate surface having irregularities. A step of forming a protective film by applying a composition having a weight ratio of phenol resin to thermoplastic resin of 100: 40 to 100: 300 and a viscosity at 25 ° C. of 4 to 10,000 mPa · s, Thereafter, the substrate manufacturing method includes a step of processing the back surface of the substrate surface coated with the protective film.

  With the above-described configuration, the composition for a substrate surface protective film of the present invention has a good resin embedding performance with respect to deep concave and convex portions at the time of manufacturing MEMS or the like, and the bottom portion of the concave portion is also well filled and protected. A gap between the film and the substrate is prevented from being generated. In addition, adhesion of the chuck in the manufacturing process is suppressed, and inconveniences that hinder the progress of the process are prevented. Further, the generation of cracks in the protective film due to heating is suppressed in the manufacturing process, and peeling after processing is easy.

  Therefore, the manufacturing method of the board | substrate using the composition for board | substrate surface protective films of this invention can be applied suitably for manufacture of MEMS etc.

  As the phenol resin, those having a softening point of 140 ° C. or higher measured by the ring and ball method are used. When the softening point is less than 140 ° C., adhesiveness is generated during heating, and it becomes inconvenient that the electrostatic chuck cannot be removed due to heat during dry etching. Preferably it is 150 degreeC or more.

  The molecular weight of the phenol resin is preferably 2000 to 20000 in terms of weight average molecular weight.

  As said phenol resin, the novolak resin etc. which have a repeating unit represented by following General formula (1) can be mentioned, for example.

  In the general formula (1), R1 to R3 each independently represents a hydrogen atom, a hydroxyl group, an alkoxyl group having 1 to 2 carbon atoms (methoxy, ethoxy, etc.) or an alkyl group having 1 to 10 carbon atoms, preferably , A hydroxyl group, and an alkyl group having 1 to 4 carbon atoms (methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, etc.), more preferably a hydroxyl group or a methyl group.

  R4 to R5 may each independently have a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a halogen atom (such as a chlorine atom), a hydroxyl group, or an alkyl group having 1 to 5 carbon atoms as a substituent. Represents a good phenyl group. However, in the entire repeating unit represented by the general formula (1), at least a part of R4 and R5 is a methyl group, a phenyl group, or a hydroxyphenyl group. Preferably, the proportion of repeating units in which R4 and / or R5 is a methyl group, a phenyl group, or a hydroxyphenyl group is 20 to 100%.

  In the whole repeating unit represented by the general formula (1), a plurality of R1, R2, R3, R4 and R5 may be the same or different from each other.

  The novolak resin can be obtained by reacting phenols with aldehydes or ketones in the presence of an acidic catalyst (for example, oxalic acid or p-toluenesulfonic acid).

  Examples of the phenols include phenol, o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, and 3,4- Xylenol, 3,5-xylenol, 2,3,5-trimethylphenol, 2,3,6-trimethylphenol, 2-t-butylphenol, 3-t-butylphenol, 4-t-butylphenol, 2-methylresorcinol, 4 -Methylresorcinol, 5-methylresorcinol, 4-t-butylcatechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol, 2-methoxy- 5-methylphenol, 2-t-butyl-5- Examples include methylphenol and pyrogallol. These can be used alone or in combination of two or more.

  In the present invention, as phenols, pyrogallol or m-cresol and other phenols such as p-cresol, 2,4-xylenol, 2,5-xylenol and 3,5-xylenol from the viewpoint of the performance of the resulting insulating film. It is preferable to use in combination with at least one selected from 5-xylenol. In this case, the weight ratio of m-cresol and the other phenols is preferably 25:75 to 85:15, more preferably 30:70 to 70:30.

  Examples of the aldehydes include formaldehyde, formalin, paraformaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, phenylacetaldehyde, α-phenylpropionaldehyde, β-phenylpropionaldehyde, o-hydroxybenzaldehyde, m-hydroxybenzaldehyde, p-hydroxy. Examples include benzaldehyde, o-chlorobenzaldehyde, m-chlorobenzaldehyde, p-chlorobenzaldehyde, o-methylbenzaldehyde, m-methylbenzaldehyde, p-methylbenzaldehyde, p-ethylbenzaldehyde, pn-butylbenzaldehyde, terephthalaldehyde and the like. . Examples of ketones include acetone, methyl ethyl ketone, diethyl ketone, and diphenyl ketone. These can be used alone or in combination of two or more. Among them, aromatic aldehydes are preferable because high Tg can be achieved.

  The said thermoplastic resin uses what has Tg of 70 degrees C or less. When Tg is higher than 70 ° C., the flexibility of the coating film is insufficient, which is disadvantageous. Preferably it is 40 degrees C or less. The lower limit is preferably −60 ° C., more preferably −20 ° C.

  The Tg of the thermoplastic resin can be measured by quantifying the temperature when measured at a DSC heating rate of 3 ° C./min.

  The molecular weight of the thermoplastic resin is preferably 10,000 to 100,000 in terms of weight average molecular weight, and more preferably 30,000 to 60,000.

  Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, poly (meth) acrylate, (meth) acrylonitrile-styrene resin, (meth) acrylonitrile-butadiene-styrene resin, vinyl chloride, polyamide, polyacetal, polyethylene terephthalate, poly Examples include butylene terephthalate, polycarbonate, polyphenylene sulfide, polyether ketone, polytetrafluoroethylene, polyethylene imide, polysulfone, polyamide imide, and ultra high molecular weight polyethylene. Among these, acrylic resins (polyacrylate and polymethacrylate) are preferable from the viewpoints of workability and ease of design. These thermoplastic resins may be used independently and 2 or more types may be used together.

  The content weight ratio of the phenol resin to the thermoplastic resin is 100: 40 to 100: 300. When the blending amount of the thermoplastic resin with respect to the phenol resin is less than this range, the effect of suppressing crack resistance is insufficient, and when it is more than this range, the surface tackiness is increased, both of which are disadvantageous. Preferably, the content weight ratio of the phenol resin to the thermoplastic resin is 100: 50 to 100: 200.

  Examples of the organic solvent include alcohols such as methanol and ethanol; ethers such as tetrahydrofuran; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol methyl ethyl ether, and ethylene glycol monoethyl ether; methyl cellosolve Ethylene glycol alkyl ether acetates such as acetate and ethyl cellosolve acetate; Diethylene glycols such as diethylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; Propylene glycol alkyl ether acetates such as ethylene glycol methyl ether acetate and propylene glycol ethyl ether acetate; aromatic hydrocarbons such as toluene and xylene; methyl ethyl ketone, methyl amyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone Ketones such as; and ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydroxy-2-methylbutane Acid methyl, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl acetate, butyl acetate, Include methyl acid, esters such as ethyl lactate. Among these, glycol ethers, alkylene glycol alkyl ether acetates, diethylene glycol dialkyl ethers and diethylene glycols are preferable. More preferred are ethyl 3-ethoxypropionate, ethyl lactate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, methyl amyl ketone, and diethylene glycol ethyl methyl ether. These solvents may be used alone or in combination of two or more.

  A leveling agent can be further mix | blended with the composition for substrate surface protection films of this invention as needed. By blending the leveling agent, the smoothness of the protective film surface can be achieved quickly, which may be advantageous in the production process. Examples of the leveling agent include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, and other polyoxyethylene alkyl ethers. Nonionic surfactants such as polyoxyethylene dialkyl esters such as polyoxyethylene dilaurate and polyoxyethylene distearate; Ftop EF301, 303 and 352 (above, trade name, Shin-Akita Kasei) (Made by Co., Ltd.), MegaFuck F171, F172, F173, R-08, R-08, R-30 (trade name, manufactured by Dainippon Ink & Chemicals, Inc.), Florard FC-430, C-431 (trade name, manufactured by Sumitomo 3M Limited), Asahi Guard AG710, Surflon S-382, SC-101, SC-102, SC-103, SC-104, SC-105 SC-106 (above, trade name, manufactured by Asahi Glass Co., Ltd.), etc .; organosiloxane polymer KP341 (above, trade name, manufactured by Shin-Etsu Chemical Co., Ltd.); (meth) acrylic acid series Copolymer polyflow no. Examples include acrylic surfactants such as 57, 75, and 95 (trade names, manufactured by Kyoeisha Yushi Chemical Co., Ltd.). Two or more of these may be used. Of these, acrylic surfactants are preferred because of their defoaming properties when using thick films.

  The blending amount of the leveling agent is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the total of the phenol resin and the thermoplastic resin. .

  The composition for a substrate surface protective film of the present invention has a viscosity at 25 ° C. of 4 to 10,000 mPa · s. If the viscosity is lower than the above range, the coating property is insufficient, and if it is higher than the above range, the coating property may be insufficient due to the excessively high viscosity, both of which are disadvantageous. Preferably it is 100-7000 mPa * s, More preferably, it is 400-3000 mPa * s.

  In the present invention, the viscosity can be measured in a constant temperature bath of 25.0 ° C. using a Canon-Fenske viscometer.

  The composition for a substrate surface protective film of the present invention can be produced by mixing each component in a predetermined amount by a known method. For example, a disperser, a mixer, a kneader, a homogenizer, a three roll It can obtain with the manufacturing method which has the process of mixing using well-known means, such as. Moreover, the composition liquid prepared as mentioned above is usually filtered before use. Examples of the filtering means include a Millipore filter having a pore diameter of 0.05 to 1.0 μm.

  Examples of the method for producing a substrate using the composition for substrate surface protective film of the present invention include, for example, applying the composition for substrate surface protective film of the present invention to a substrate surface that is finely processed and having irregularities, and then protecting the film. And a process for processing the back surface of the substrate surface covered with the protective film, and a method for manufacturing the substrate.

  The substrate surface having irregularities may have, for example, a concave portion having a depth / hole diameter ratio value of 1 or more, and the irregularity step may be a deep microstructure having a depth of, for example, 100 μm. It is not a thing. Such micromachined irregularities can be formed by a micromachining technique that forms a fine structure of millimeter to micrometer order, such as etching, lithography, laser processing, and ultrasonic processing. Examples of the substrate include a semiconductor substrate, a glass substrate, and an organic material substrate.

  In the step of forming the protective film, the composition of the present invention is applied to the surface of the substrate by a technique such as spin coating, dip coating, spray coating, or roll coating. In the case of spin coating, for example, coating is performed at about 500 to 6000 rpm. The coating thickness may be about several tens of μm (for example, 20 to 30 μm) on the flat portion of the substrate.

  The molding conditions for the protective film include a drying temperature of 80 to 140 ° C., more preferably 90 to 130 ° C., a curing time of 1 to 30 minutes, and more preferably 2 to 10 minutes. , 0.5-3 hours.

  In the step of processing the back surface of the substrate surface covered with the protective film, for example, processing such as dry etching, wet etching, polishing, and grinding can be performed. In the case of dry etching, for example, a deep RIE method or a Bosch process can be performed using a fluorine-based gas.

  Usually, the protective film is easily cracked during the dry etching process, and the possibility is significantly reduced by using the composition for a substrate surface protective film of the present invention.

  The manufacturing method of the present invention can include a step of peeling the protective film with a peeling solution after the step of processing the back surface. Examples of the stripper include N-methyl-2-pyrrolidone (NMP), acetone, methyl ethyl ketone (MEK), and ethyl acetate. In the peeling step, the peeling solution can be further removed by a method such as ultrasonic treatment or spray cleaning.

  In the manufacturing method of the present invention, the manufacturing process can further include a dicing process and a scribe process. The dicing process can be performed in the same manner as the silicon wafer cutting process in the semiconductor post-process. The scribing process can be performed in the same manner as the scribing process for glass or the like. In this case, the dicing process is usually performed after the protective film is peeled off. However, since the protective film can be protected from shavings during dicing, the protective film is peeled off at the final step of the dicing process or the scribe process. Is desirable.

  The substrate manufacturing method of the present invention can be applied to various substrates such as MEMS, LEDs, power devices, semiconductor circuits, liquid crystal display devices, touch panels and the like, and can be suitably applied particularly to the manufacture of double-sided substrates. is there.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the following, the meanings of the abbreviations are as follows.
Resin 1: Mw = 10,000, softening point 190 ° C. measured by ring and ball method (phenol resin taken out by polycondensation of metacresol 60 phr / paracresol 40 phr / benzaldehyde 100 phr by a usual method).
Resin 2: Mw = 8000, softening point 150 ° C. measured by ring and ball method (phenol resin taken out by polycondensation of metacresol 60 phr / paracresol 40 phr / benzaldehyde 50 phr / formaldehyde 50 phr by a usual method).
EPR6040A: phenol resin, Mw = 2800, softening point measured by ring and ball method, 130 ° C., manufactured by Asahi Organic Materials Co., Ltd.
Resin A: Acrylic resin (Mw = 43,000, Tg = 80 ° C.) obtained by copolymerization of methyl methacrylate 50 phr, butyl methacrylate 30 phr, and methacrylic acid 20 phr.
Resin B: An acrylic resin (Mw = 46,000, Tg = 65 ° C.) obtained by copolymerization of 55 phr methyl methacrylate, 15 phr butyl acrylate, and 20 phr methacrylic acid.
Resin C: Acrylic resin copolymerized with 40 phr methyl methacrylate, 40 phr butyl acrylate, and 20 phr methacrylic acid (Mw = 30,000, Tg = 19 ° C.).
Resin D: Acrylic resin (Mw = 40,000, Tg = −4 ° C.) obtained by copolymerization of 30 phr of methyl methacrylate, 60 phr of butyl acrylate, and 20 phr of methacrylic acid.
ACA Z320: acrylic resin, Mw = 23,000, Tg = 140 ° C., manufactured by Daicel-Cytec.
BYK-381: Acrylic leveling agent, manufactured by BYK Japan.
PGMEA: Propylene glycol monomethyl ether acetate, manufactured by Daicel Chemical Industries.

Examples 1-6, Comparative Examples 1-6
Preparation of Composition for Protective Film Each component was mixed with Awatori Rentaro ARV-310 (Sinky) according to the formulation (parts by weight) shown in Table 1 to obtain a composition for protective film.

Preparation of Evaluation Substrate Next, each composition was spun onto a semiconductor substrate having a recess having a depth / hole diameter ratio value of 3 and a recess / protrusion step of 100 μm and having a fine structure deeply etched by dry etching. Then, a protective film having a thickness of 5 to 30 μm was applied on the flat portion. Next, the solvent was dried at 120 ° C. for 5 minutes, and the film forming property, surface tack property, crack resistance, chemical resistance, and peelability were evaluated by the following methods. The results are shown in Table 2.

Evaluation method <Evaluation of film formability>
Using the excavator SAICAS DN-5S (Daipura Wintes), the state of the film was observed for the protective film sample obtained above. When the film can be scraped without causing cracks and breakage, it is indicated by a symbol (◯), and when it is cracked or broken, it is indicated by a symbol (x).
<Surface tackiness evaluation>
The protective film surface was set facing the electrostatic chuck side of the apparatus, and the back surface side of the protective film was dry-etched using RIE-200iP, then removed from the apparatus, and the protective film was peeled off and the surface roughness was observed. . At this time, when the protective film does not peel off (transfer to the apparatus) due to the heat of the dry etching process, it is indicated by a symbol (◯), and when the peeling occurs, it is indicated by a symbol (X).
<Crack resistance evaluation>
After the dry etching treatment, cracks were observed using an optical microscope. When no crack was observed, it was indicated by a symbol (◯), when a crack was observed, the symbol (X) was indicated by a symbol (Δ) when there was a problem.
<Chemical resistance evaluation>
After the dry etching treatment, the protective film sample was immersed in a 5% aqueous ammonium fluoride solution at 23 ° C. for 10 minutes, and the penetration of the chemical solution under the protective film was observed. When there was no penetration, it was indicated by a symbol (◯), when penetration was observed, it was indicated by a symbol (X), and when there was a problem, it was indicated by a symbol (Δ). However, Comparative Examples 1 and 2 were not evaluated because cracks occurred and evaluation could not be continued.
<Peelability evaluation>
After the dry etching treatment, the protective film sample was treated with NMP / 80 ° C./60 minutes, and the peeling residue was observed. The symbol (◯) indicates that no peeling residue is generated, and the symbol (×) indicates that a residue is generated. However, Comparative Examples 1 and 2 were not evaluated because cracks occurred and evaluation could not be continued.

  From these results, it was proved that the compositions of the examples were excellent in crack resistance, had good resin embedding performance with respect to the deeply uneven fine irregularities, and suppressed adhesiveness of the protective film. .

Claims (9)

A phenol resin having a softening point of 140 ° C. or higher measured by the ring and ball method, a thermoplastic resin having a Tg of 70 ° C. or lower, and an organic solvent, and the content weight ratio of the phenol resin to the thermoplastic resin is 100: The composition for substrate surface protective films which is 50-100: 300 and whose viscosity in 25 degreeC is 4-10000 mPa * s.   The composition according to claim 1, wherein the phenol resin is a novolak resin which is a reaction product of phenols and aromatic aldehydes.   The composition according to claim 1 or 2, wherein the thermoplastic resin is an acrylic resin.   Furthermore, the composition in any one of Claims 1-3 containing a leveling agent.   The composition according to any one of claims 1 to 4, wherein the viscosity at 25 ° C is 100 to 7000 mPa · s.   Containing a phenolic resin having a softening point of 140 ° C. or higher, a thermoplastic resin having a Tg of 70 ° C. or lower, and an organic solvent on a micro-processed substrate surface having irregularities; A step of applying a composition having a weight ratio with the thermoplastic resin of 100: 40 to 100: 300 and a viscosity at 25 ° C. of 4 to 10000 mPa · s to form a protective film, and then the protection A method for manufacturing a substrate, comprising: processing a back surface of a substrate surface covered with a film.   The manufacturing method according to claim 6, wherein the uneven substrate surface has a recess having a depth / hole diameter ratio of 1 or more.   The manufacturing method according to claim 6 or 7, further comprising a step of peeling the protective film with a peeling liquid after the step of processing the back surface of the substrate surface coated with the protective film.   Furthermore, the manufacturing method in any one of Claims 6-8 including a dicing process and a scribe process.